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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- G N A T . M B B S _ F L O A T _ R A N D O M --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
-- --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. The copyright notice above, and the license provisions that follow --
-- apply solely to the contents of the part following the private keyword. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- The implementation used in this package was contributed by
-- Robert Eachus. It is based on the work of L. Blum, M. Blum, and
-- M. Shub, SIAM Journal of Computing, Vol 15. No 2, May 1986. The
-- particular choices for P and Q chosen here guarantee a period of
-- 562,085,314,430,582 (about 2**49), and the generated sequence has
-- excellent randomness properties. For further details, see the
-- paper "Fast Generation of Trustworthy Random Numbers", by Robert
-- Eachus, which describes both the algorithm and the efficient
-- implementation approach used here.
-- Formerly, this package was Ada.Numerics.Float_Random. It is retained
-- here in part to allow users to reconstruct number sequences generated
-- by previous versions.
with Interfaces;
package GNAT.MBBS_Float_Random is
-- Basic facilities
type Generator is limited private;
subtype Uniformly_Distributed is Float range 0.0 .. 1.0;
function Random (Gen : Generator) return Uniformly_Distributed;
procedure Reset (Gen : Generator);
procedure Reset (Gen : Generator; Initiator : Integer);
-- Advanced facilities
type State is private;
procedure Save (Gen : Generator; To_State : out State);
procedure Reset (Gen : Generator; From_State : State);
Max_Image_Width : constant := 80;
function Image (Of_State : State) return String;
function Value (Coded_State : String) return State;
private
type Int is new Interfaces.Integer_32;
-- We prefer to use 14 digits for Flt, but some targets are more limited
type Flt is digits Positive'Min (14, Long_Long_Float'Digits);
K1 : constant := 94_833_359;
K1F : constant := 94_833_359.0;
K2 : constant := 47_416_679;
K2F : constant := 47_416_679.0;
Scal : constant := 1.0 / (K1F * K2F);
type State is record
X1 : Int := 2999 ** 2; -- Square mod p
X2 : Int := 1439 ** 2; -- Square mod q
P : Int := K1;
Q : Int := K2;
X : Int := 1;
Scl : Flt := Scal;
end record;
type Generator is limited record
Gen_State : State;
end record;
end GNAT.MBBS_Float_Random;
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